Thayer's Note:

a
As with other Confederate officers, Cullum's Register omits his war record; he rose to the rank of Colonel and was a prisoner of war. His life and career are detailed, with much interesting incident, in Chapters 4 thru 7 of The Glengarry McDonalds of Virginia by his daughter Flora McDonald Williams,
online in a very irritatingly ad-ridden site: avoid clicking on anything there. Not mentioned on that site, his son Hunter McDonald, for whom Robert E. Lee once wrote a letter of recommendation
(Freeman, R. E. Lee, IV, 277)
would eventually write General Lee after Appomattox.

Images with borders lead to more information.
The thicker the border, the more information.
(Details here.)